True, startd cron's can (and have) been used to do all sorts of
things - but I haven't seen one applied to do host-level
concurrency limits (successfully). The "cron"/timeperiod nature
makes doing resource counters unsafe for resource reservation. Do
you have an example of one of those, or is it (like I currently
believe) a gap in functionality that you end up having to build up
custom slot types around to handle?
For instance, say I have a SAN-attached host and want to enable no
more than 3 concurrent SAN IO jobs while also enabling other job
types. Today I'd have to set up a special partitionable slot with a
SAN attribute and start expression to only allow SAN jobs and do
something like dedicating 3 CPU's and some amount of RAM towards
that partitionable slot. Or make 3 SAN slots with dedicated memory
resources. And then add a partitionable slot for all remaining
CPU, memory, and local disk resourcse. There's no way to apply a
"SAN" resource counter, and no way to alter the number "3" live
based on actual SAN link utilization or storage subsystem latency.
Right?